This paper reports on a corpus-based comparison of the use of taboo words amongst middle/upper class teenage girls in London and Madrid. Two corpora of spontaneous conversation were used for the comparison; these showed that the most frequent words used by both groups had sexual reference, followed by words to do with bodily functions. It also pointed to a higher frequency of taboo words in the London girls’ conversations, while the Madrid girls had a slightly higher preference for sexual words. The qualitative part of the study, which deals with the reasons for teenagers’ use of taboo words and with their various functions in the discourse, reveals that special emphasis is put on phatic use.